.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996
.\"
.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" the License, or (at your option) any later version.
.\"
.\" The GNU General Public License's references to "object code"
.\" and "executables" are to be interpreted as the output of any
.\" document formatting or typesetting system, including
.\" intermediate and printed output.
.\"
.\" This manual is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public
.\" License along with this manual; if not, see
.\" <http://www.gnu.org/licenses/>.
.\" %%%LICENSE_END
.\"
.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
.\"            First version written
.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
.\"            revision
.\"
.TH SCHED_YIELD 2 2021-03-22 "Linux" "Linux Programmer's Manual"
.SH NAME
sched_yield \- yield the processor
.SH SYNOPSIS
.nf
.B #include <sched.h>
.PP
.B int sched_yield(void);
.fi
.SH DESCRIPTION
.BR sched_yield ()
causes the calling thread to relinquish the CPU.
The thread is moved to the end of the queue for its static
priority and a new thread gets to run.
.SH RETURN VALUE
On success,
.BR sched_yield ()
returns 0.
On error, \-1 is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
In the Linux implementation,
.BR sched_yield ()
always succeeds.
.SH CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
.SH NOTES
If the calling thread is the only thread in the highest
priority list at that time,
it will continue to run after a call to
.BR sched_yield ().
.PP
POSIX systems on which
.BR sched_yield ()
is available define
.B _POSIX_PRIORITY_SCHEDULING
in
.IR <unistd.h> .
.PP
Strategic calls to
.BR sched_yield ()
can improve performance by giving other threads or processes
a chance to run when (heavily) contended resources (e.g., mutexes)
have been released by the caller.
Avoid calling
.BR sched_yield ()
unnecessarily or inappropriately
(e.g., when resources needed by other
schedulable threads are still held by the caller),
since doing so will result in unnecessary context switches,
which will degrade system performance.
.PP
.BR sched_yield ()
is intended for use with real-time scheduling policies (i.e.,
.BR SCHED_FIFO
or
.BR SCHED_RR ).
Use of
.BR sched_yield ()
with nondeterministic scheduling policies such as
.BR SCHED_OTHER
is unspecified and very likely means your application design is broken.
.SH SEE ALSO
.BR sched (7)
.SH COLOPHON
This page is part of release 5.13 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.
